Guardtime™ Keyless Signature Guardtime™ is an award winning Keyless Signature Infrastructure (KSI) solution provider which provides proof of signing authority, time of the signature, and integrity of all data located in the cloud, on disk, and in transit. The signature never expires and its verification is based solely on mathematics, eliminating the need for secrets, keys, or human intervention. Companies around the world from different sectors and industries trusted Guardtime™ to deliver undeniable proof that the authentication and authorization events occurred as expected and reported.